The goal of this research project is to develop a method of noninvasively imaging the diaphragmatic surface to directly measure its mechanical activity so that indirect quantitative measurements of tidal volume, air flow and general pulmonary function can be performed. Characterization of diaphragmatic movement dynamics may be of vital importance in the assessment of respiratory function and significant deviations from a predetermined normal group may become an important indicator of pulmonary function. Other related areas of research include: (1) Evaluation of radiofrequency phrenic nerve stimulation as a respiratory support technique in adults with chronic lung disease and sleep apnea and neonates with recurrent apneic spells or hypoventilation who have experiened "near-miss" or aborted sudden infant death episodes. (2) Development of a mathematical computer simulation model for characterizing respiratory function using noninvasively derived data. Analysis of diaphragm dynamics will be accomplished by application of image techniques to fluoroscopically derived video views of the lung and diaphragm region. This approach employs an electronic technique to noninvasively track and record diaphragm motion and velocity, by using "track-while-scan" video methods. Application of this technique could lead to an alternative noninvasive approach for evaluating respiratoy function, in vivo. Moreover, if noninvasive assessment of diaphragmatic motion proves to be an accurate predictor of pulmonary function, various therapeutic regimes may be evaluated in patients with chronic lung disease with minimal risk and discomfort.